The long term goals of my research program are to find novel functions for both estrogens and estrogen response proteins, and then to identify the molecular mechanisms mediating these functions. This research will lead to a better understanding of estrogens' developmental, physiological, and biochemical roles in humans, and additionally will add to our general understanding of how estrogenic chemicals in the environment can impinge upon women's health. To pursue these research goals, we 'knocked out' the estrogen receptor (ER) gene in mice via homologous recombination and asked the following question: Would an ER- minus mouse, which lacked the classic full length ER protein, respond to any known estrogen, estrogen metabolite, or exogenous (natural or synthetic) estrogen analog? If ER-minus mice did respond, then we would know that at least one estrogen response protein other than ER exists. The working hypothesis was that several non-ER response proteins exist and that in transgenic ER-minus mice we would see a response to some estrogens, such as the environmental estrogen, methoxychlor. We have found in ER-minus mice a uterine lactoferrin mRNA response to methoxychlor and kepone, but not to estradiol. We propose that the putative methoxychlor receptor will elicit additional responses distinct from estradiol and the classic ER protein. We now hypothesize that: A) methoxychlor and other biologically important estrogens work, at least in part, through their own unique non-classical, estrogen response (NCER) proteins; and B) NCER "receptors" can be readily characterized in the ER-minus mouse background. Using this mouse model system we propose to characterize the methoxychlor response and the putative methoxychlor receptor. Specifically, we propose to: Aim #1: Characterize lactoferrin mRNA responses to methoxychlor, kepone, and o7p'DDT in ER-minus mice; Aim #2: Characterize the putative methoxychlor receptor in uteri from ER-minus mice; and Aim #3: Compare the specificity of the responses to methoxychlor with those of estradiol, kepone, and o7p'DDT in ER-minus mice.Characterization of the putative methoxychlor, an important environmental endocrine disrupter.